In artificial hands of the aforedescribed type, generally each gripper is swingable about an axis which extends transversely and usually perpendicularly, to the axis of the prosthesis connector, i.e. the threaded or bayonet fixture by which the artificial hand is fastened to the remainder of the prosthesis; hereinafter, this fixture, which has a defined axis, will be described as a connector.
As a consequence of this swingable movement of each gripper about a respective axis transverse to the axis of the connector, the gripper movement is a scissor or tongs action enabling the jaws to engage an object between them.
This construction has the disadvantage that it is difficult to grip objects which have gripping surfaces located relatively high above the surface upon which the object stands. This is because it is difficult to place the artificial hand in a gripping position without bending the arm at such an angle that the surface on which the object rests will interfere with engagement of the object between the thumb and gripping finger of the artificial hand. Furthermore, even if engagement of the object is not prevented, the required orientation of the arm for engagement with high gripping surfaces of an object standing on a table, for example, makes the gripping motion extremely awkward and difficult to carry out.